1. Field of the Invention
The present invention relates to a positioning device which moves an output component to a position using two separate types of motion. More specifically, the present invention relates to a positioning device for automatically shifting gears in an transmission of a motor vehicle.
2. Description of the Related Art
According to DE 43 11 855 A1, a positioning device is known for positioning a gearshift lever shaft of a transmission of a motor vehicle by using two drives for two separate types of motion. In this positioning device, a first drive is arranged vertically relative to a second drive. As FIG. 19 of that reference shows, the twisting or rotating of the gearshift lever shaft is produced by the first drive. The first drive linearly drives a gear rack, which engages a gear wheel. The gear wheel is fixedly connected to the gearshift lever shaft. An axial sliding of the gearshift lever shaft is effected by the second drive. To transmit the sliding movement, the second drive is actively connected to the gearshift lever shaft, so that the linear movement of the second drive is transmitted directly to the gearshift lever shaft.
Because of this sliding movement, the gear wheel that is fixedly connected to the gearshift lever shaft to transmit the rotary movement must be long enough axially to ensure that the gear rack and the gear wheel remain engaged throughout the entire linear movement of the gearshift lever.
A problem with this transmission mechanism, is that the teeth of the gear wheel are constantly engaged with the teeth of the gear rack and rub against each other when the gearshift lever shaft is shifted. This causes a heavy stress on the gear teeth. The teeth become worn, increasing the play between the engaged teeth. Particularly when positioning devices for positioning a gearshift lever shaft of a transmission are used, operability must be ensured for many shifting procedures. For this reason, the transmission mechanism described above is unsuitable for use in positioning the gearshift lever shaft of a transmission.